Switching devices having a first and a second connection as well as a control connection are known. So called field effect transistors are frequently used as switching devices.
A disadvantage of these switching devices is that they do not guarantee protection against polarity reversal. If the supply voltage is installed incorrectly polarized, the case can arise in which there is a continuous current in the load. If the load is, for example, a solenoid valve, this can lead, for example, to the fact that the solenoid valve remains permanently in one position independent of the drive signal. The case can arise with other loads that the switching device and/or the load to which current is applied by the switching device, or the consumer is damaged or even destroyed.